The invention relates to a fuel tank filler neck arrangement for motor vehicles at which a receiving element for a fuel injection nozzle and an end-face filling collar are provided, a fuel filler tube of the fuel injection nozzle projecting by sections into the filler neck during the refueling.
In the case of a known fuel tank of the initially mentioned type disclosed in German Published Unexamined Application No. (DE-OS 22 08 189), the filler neck, over its whole longitudinal course, has an approximately constant cross-section. When fuel is filled into this fuel tank, an excess pressure is created in the interior of the tank. Soon after the fuel injection nozzle is switched off, the energy that acted in the filling direction through the fuel injection nozzle is no longer present and the pressure on the inside of the fuel tank is compensated with the fuel column being pressed upward by and in the filler neck. Because of the design of the cross-section of the filler neck, the rising fuel column cannot expand and is therefore thrown to the outside at a relatively high speed, causing not only fuel to be released to the outside but possibly also spraying the person who is refueling.
German Published Examined Application No. (DE-AS 23 53 448) shows a fuel tank having a filler neck, where at the filler neck, below the inserting level of the fuel filler nozzle, a segregating space is formed that has a cross-section that differs from the cross-section of the filler neck. This segregating space, during the refueling process, is used for the separation of the air flowing upwards from the filler neck from the fuel flowing into the fuel tank. This arrangement also has the disadvantage that after the switching off of the fuel filler nozzle, fuel sprays out of the filler neck, because no escape measures are taken for the fuel volume that is being pressed upward; even before the fuel filler nozzle is switched off, the segregation space is filled completely with fuel.
It is an objective of the invention to develop a fuel tank filler neck in such a way that a spraying of fuel out of the filler neck after the switching-off of the fuel filler nozzle is reliably prevented.
According to the invention, this objective is achieved by providing a widening of the upper part of the filler neck to form fuel accumulating expansion space. In especially preferred embodiments, the widening commences at a position adjacent to just below the bottom of the fuel filler nozzle when in its innermost fuel supplying position. In certain preferred embodiments, a cylindrically-formed nozzel receiving element is connected at a collar surrounding the vehicle gas filling opening and protrudes inwardly of the opening with a guide for guiding the fuel filler nozzle. The widened section expansion space of the upper part of the filler neck extends concentrically around the nozzle receiving element and exhibits its maximum diameter adjacent the lower end of the nozzle receiving element. This widened section is narrowed at its top to merge with the connection of the nozzle receiving element adjacent the collar surrounding the gas filling opening in the vehicle body. In certain preferred embodiments, a fuel tank venting device opens into the expansion space adjacent the maximum diameter section of the widened section of the filler neck. In especially preferred embodiments the filler neck, including the widened section, is constructed as an integral one-piece component formed by blow molding of plastic material. The maximum diameter of the widened space is at least twice the diameter of the diameter of the nozzle receiving element.
The main advantages achieved by means of the invention are that by means of the expansion space developed in the area of the fuel filler nozzle at the filler neck, a perfect complete filling with fuel of the fuel tank is ensured. The fuel that is pressed upward, after the switching-off of the fuel filler nozzle, can escape toward the side, into the relatively large-volume expansion space and can expand there. As a result, an emerging of fuel toward the outside is avoided which not only meets the requirement of an improved protection with respect to emissions, but also ensures that the clothes of the person who is refueling are not sprayed with fuel. In addition, the filler neck with the expansion space is constructionally simple and can be produced in a cost-effective way.
Further objects, features and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings, which show for purposes of illustration only, embodiments constructed in accordance with the present invention.